Some airplane pilots struggle to achieve smooth landings on a consistent basis. Skill, experience, visual perception, fatigue and/or distraction are factors that may play a role in a pilot's ability to land a plane smoothly. Also, landing at night, during a power outage at the airport, when there is a runway lighting issue, or on glassy water may present additional challenges. A good landing is assured if the pilot can touch the runway under control with low vertical velocity.